Present views of carnitine metabolism indicate that dietary or biosynthesized carnitine is transported from the liver to the tissues where it is taken by the relevant tissues for explicit functions of the cell. Widely different carnitine concentrations in the tissues imply that specific uptake mechanisms rather than passive diffusion are operative. We have considerable evidence for the existence of carnitine binding proteins in rat tissue (e.g., liver, heart, muscle) and the blood and have developed a (3H) carnitine binding assay to monitor carnitine-protein binding activity. Efforts will continue to localize such activity in cell fractions and purify the relevant proteins to permit appropriate detailed biochemical characterization and kinetic studies of these carnitine binding proteins. Unpublished observations from our laboratory indicate the existence of lysine and exsilon-N-methylated lysine derivatives covalently bound to lipid fractions in rat liver. We suspect such forms of lysine may participate in a pathway of carnitine in the synthesis of previously unrecognized functional form(s) of carnitine. Synthesis of epsilon-N-trimethyllysine from lysine (or phosphatidyllysine of microbial origin) will be pursued, under conditions where protein synthesis in inoperative and with particular attention given to the possibility of phospholipid participation in this process.